I have a checkpoint 680 with the L2TP windows VPN setup. I was able to connect a mac in about 5 minutes. XP took 2 days but I was finally able to connect. Windows 7 will connect but when you go to the status window for the vpn it says it is not connected to the network. I have triple checked that all the settings are the same between the xp and windows 7 machine and one of our vendors was able to duplicate this behavior. They can connect with xp but not 7. I have setup the connection via Checkpoint's instructions as follows:
1. In options deselect include windows logon domain
2. In ppp settings only lcp connections should be checked
3. Under security L2TP should be selected with the preshared secret in the advanced settings
4. Under Data Encryption select Optional encryption
5. Select allow these protocols and have only unencrypted password selected
6. When connecting for the username type the usename only. Don’t include the Domain. Type your account password and you should be in.